A breakdown of the link between the Arctic and North Atlantic Oscillations in warm climate projections

<table><tbody><tr><td>The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) are climate variability modes significantly affecting temperature and precipitation variability in the mid-latitudes of the Northern hemisphere. In this study, we use both reanalysis data and model historical and warmer climate simulations to show that the relation between the two oscillations may change dramatically in a different climate. In the current climate, these two climate modes are highly correlated, as they are both strongly influenced by downward propagation of stratospheric anomalies into the troposphere. When considering a warmer climate scenario (RCP8.5 in the XXIII century), the correlation between NAO and AO drops significantly, revealing that they become two separate modes of variability. The stratosphere remains an important precursor for NAO, while the AO consistently precede stratospheric anomalies. The analysis suggests that these changes are owed to land-sea thermal contrast intensification in the Pacific region, which becomes more favorable for storm variability.</td> </tr></tbody></table>

The North Atlantic Oscillation and the Arctic Oscillation favour harmful algal blooms in SW Europe

Harmful Algae ◽

10.1016/j.hal.2014.07.008 ◽

2014 ◽

Vol 39 ◽

pp. 121-126 ◽

Cited By ~ 8

Author(s):

José C. Báez ◽

Raimundo Real ◽

Victoria López-Rodas ◽

Eduardo Costas ◽

A. Enrique Salvo ◽

...

Keyword(s):

North Atlantic ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Arctic Oscillation ◽

The Arctic ◽

The North ◽

The North Atlantic ◽

The Arctic Oscillation ◽

The influence of Arctic air masses on climatic conditions of the snow accumulation period in the center of the European territory of Russia

Арктика и Антарктика ◽

10.7256/2453-8922.2021.1.35112 ◽

2021 ◽

pp. 16-25

Author(s):

Julia Nikolaevna Chizhova

Keyword(s):

North Atlantic ◽

Arctic Oscillation ◽

Winter Precipitation ◽

Climatic Conditions ◽

The Arctic ◽

Air Masses ◽

The North ◽

The Arctic Oscillation ◽

The North Atlantic Oscillation ◽

The Relationship

The subject of this article is exmination of the influence of the Arctic air flow on the climatic conditions of the winter period in the center of the European territory of Russia (Moscow). In recent years, the question of the relationship between regional climatic conditions and such global circulation patterns as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AK) has become increasingly important. Based on the data of long-term observations of temperature and precipitation, the relationship with the AK and NAO was considered. For the winter months of the period 2014-2018, the back trajectories of the movement of air masses were computed for each date of precipitation to identify the sources of precipitation. The amount of winter precipitation that forms the snow cover of Moscow has no connection with either the North Atlantic Oscillation or the Arctic Oscillation. The Moscow region is located at the intersection of the zones of influence of positive and negative phases of both cyclonic patterns (AK and NAO), which determine the weather in the Northern Hemisphere. For the winter months, a correlation between the surface air temperature and NAO (r = 0.72) and AK (r = 0.66) was established. Winter precipitation in the center of the European territory of Russiais mainly associated with the unloading of Atlantic air masses. Arctic air masses relatively rarely invade Moscow region and bring little precipitation (their contribution does not exceed 12% of the total winter precipitation).

On monsoon character of circulation over the Barents and Kara Seas

10.5194/egusphere-egu2020-2745 ◽

2020 ◽

Author(s):

Alexander Kislov ◽

Tatiana Matveeva

Keyword(s):

Atmospheric Circulation ◽

North Atlantic ◽

Winter Season ◽

The Arctic ◽

Modes Of Variability ◽

The North ◽

The North Atlantic ◽

Barents And Kara Seas ◽

<p>This study analysed the monsoon features of atmospheric circulation in the Barents and Kara Seas, the variability of atmospheric circulation, and anomalies in temperature, precipitation, and wind speed. In a cold period, the extreme winds are southerly winds that develop in the eastern parts of cyclones. In the warm season, the extreme speeds correspond to a northerly wind in the western periphery of cyclones. The regional circulation systems were divided into ten circulation weather types, separately for each sea. Their frequencies were compared with different indexes, describing the main modes of variability for the arctic region (the North Atlantic Oscillation, the summer North Atlantic Oscillation, the Scandinavia&#160;teleconnection pattern, the Siberian High). In the winter season, the monsoon currents from land to sea occur only when the North Atlantic Oscillation index is positive. With the prevalence of other modes of variability, the direction of the winds can be different, and this causes the monsoon regularity to be stochastic. In summer, the northern streams move on the western periphery of cyclones, regenerating and stabilizing over the Kara Sea.</p><p>The work was supported by the grant of the Russian Foundation for Basic Research (RFBR) [project number 18-05-60147] and this work was carried out as part of governmental&#160;assignment &#1040;&#1040;&#1040;&#1040;-&#1040;16-116032810086-4.</p>

Combined Effects of the North Atlantic Oscillation and the Arctic Oscillation on Sea Surface Temperature in the Alborán Sea

PLoS ONE ◽

10.1371/journal.pone.0062201 ◽

2013 ◽

Vol 8 (4) ◽

pp. e62201 ◽

Cited By ~ 22

Author(s):

José C. Báez ◽

Luis Gimeno ◽

Moncho Gómez-Gesteira ◽

Francisco Ferri-Yáñez ◽

Raimundo Real

Keyword(s):

Surface Temperature ◽

North Atlantic ◽

Arctic Oscillation ◽

Sea Surface ◽

The Arctic ◽

Combined Effects ◽

The North ◽

The North Atlantic ◽

The Arctic Oscillation ◽

Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

Journal of the Atmospheric Sciences ◽

10.1175/jas3719.1 ◽

2006 ◽

Vol 63 (7) ◽

pp. 1859-1877 ◽

Cited By ~ 35

Author(s):

D. Kondrashov ◽

S. Kravtsov ◽

M. Ghil

Keyword(s):

Numerical Study ◽

Singular Spectrum Analysis ◽

Low Frequency ◽

The Arctic ◽

Reduced Model ◽

The North ◽

Low Frequency Variability ◽

Intraseasonal Oscillations ◽

The Arctic Oscillation ◽

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

Trends in compound extremes of air temperature and precipitation in Eastern Europe

10.21203/rs.3.rs-1085030/v1 ◽

2021 ◽

Author(s):

Elena Vyshkvarkova ◽

Olga Sukhonos

Keyword(s):

Eastern Europe ◽

Air Temperature ◽

North Atlantic ◽

Large Scale ◽

The North ◽

Temperature And Precipitation ◽

Atmosphere System ◽

Daily Data ◽

Abstract The spatial distribution of compound extremes of air temperature and precipitation was studied over the territory of Eastern Europe for the period 1950–2018 during winter and spring. Using daily data on air temperature and precipitation, we calculated the frequency and trends of the four indices – cold/dry, cold/wet, warm/dry and warm/wet. Also, we studying the connection between these indices and large-scale processes in the ocean-atmosphere system such as North Atlantic Oscillation, East Atlantic Oscillation and Scandinavian Oscillation. The results have shown that positive trends in the region are typical of the combinations with the temperatures above the 75th percentile, i.e., the warm extremes in winter and spring. Negative trends were obtained for the cold extremes. Statistically significant increase in the number of days with warm extremes was observed in the northern parts of the region in winter and spring. The analysis of the impacts of the large-scale processes in oceans-atmosphere system showed that the North Atlantic Oscillation index has a strong positive and statistically significant correlation with the warm indices of compound extremes in the northern part of Eastern Europe in winter, while the Scandinavian Oscillation shows the opposite picture.

How Predictable Are the Arctic and North Atlantic Oscillations? Exploring the Variability and Predictability of the Northern Hemisphere

Journal of Climate ◽

10.1175/jcli-d-17-0226.1 ◽

2018 ◽

Vol 31 (3) ◽

pp. 997-1014 ◽

Cited By ~ 19

Author(s):

Daniela I. V. Domeisen ◽

Gualtiero Badin ◽

Inga M. Koszalka

Keyword(s):

Time Scales ◽

Northern Hemisphere ◽

North Atlantic ◽

Prediction Models ◽

The Arctic ◽

Ensemble Prediction ◽

Atmospheric Conditions ◽

Short Term ◽

The North ◽

ABSTRACT The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) describe the dominant part of the variability in the Northern Hemisphere extratropical troposphere. Because of the strong connection of these patterns with surface climate, recent years have shown an increased interest and an increasing skill in forecasting them. However, it is unclear what the intrinsic limits of short-term predictability for the NAO and AO patterns are. This study compares the variability and predictability of both patterns, using a range of data and index computation methods for the daily NAO and AO indices. Small deviations from Gaussianity are found along with characteristic decorrelation time scales of around one week. In the analysis of the Lyapunov spectrum it is found that predictability is not significantly different between the AO and NAO or between reanalysis products. Differences exist, however, between the indices based on EOF analysis, which exhibit predictability time scales around 12–16 days, and the station-based indices, exhibiting a longer predictability of 18–20 days. Both of these time scales indicate predictability beyond that currently obtained in ensemble prediction models for short-term predictability. Additional longer-term predictability for these patterns may be gained through local feedbacks and remote forcing mechanisms for particular atmospheric conditions.

Impacts of large-scale atmospheric circulation changes due to winter sea-ice retreat on Black Carbon transport and deposition to the Arctic

10.5194/acp-2016-1007 ◽

2016 ◽

Author(s):

Luca Pozzoli ◽

Srdan Dobricic ◽

Simone Russo ◽

Elisabetta Vignati

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

North Atlantic ◽

Large Scale ◽

Southern Oscillation ◽

The Arctic ◽

The North ◽

Ice Retreat ◽

The North Atlantic Oscillation ◽

Sea Ice Retreat

Abstract. Winter warming and sea ice retreat observed in the Arctic in the last decades determine changes of large scale atmospheric circulation pattern that may impact as well the transport of black carbon (BC) to the Arctic and its deposition on the sea ice, with possible feedbacks on the regional and global climate forcing. In this study we developed and applied a new statistical algorithm, based on the Maximum Likelihood Estimate approach, to determine how the changes of three large scale weather patterns (the North Atlantic Oscillation, the Scandinavian Blocking, and the El Nino-Southern Oscillation), associated with winter increasing temperatures and sea ice retreat in the Arctic, impact the transport of BC to the Arctic and its deposition. We found that the three atmospheric patterns together determine a decreasing winter deposition trend of BC between 1980 and 2015 in the Eastern Arctic while they increase BC deposition in the Western Arctic. The increasing trend is mainly due to the more frequent occurrences of stable high pressure systems (atmospheric blocking) near Scandinavia favouring the transport in the lower troposphere of BC from Europe and North Atlantic directly into to the Arctic. The North Atlantic Oscillation has a smaller impact on BC deposition in the Arctic, but determines an increasing BC atmospheric load over the entire Arctic Ocean with increasing BC concentrations in the upper troposphere. The El Nino-Southern Oscillation does not influence significantly the transport and deposition of BC to the Arctic. The results show that changes in atmospheric circulation due to polar atmospheric warming and reduced winter sea ice significantly impacted BC transport and deposition. The anthropogenic emission reductions applied in the last decades were, therefore, crucial to counterbalance the most likely trend of increasing BC pollution in the Arctic.

Dynamics of the ENSO Teleconnection and NAO Variability in the North Atlantic–European Late Winter

Journal of Climate ◽

10.1175/jcli-d-19-0192.1 ◽

2020 ◽

Vol 33 (3) ◽

pp. 907-923 ◽

Cited By ~ 4

Author(s):

Bianca Mezzina ◽

Javier García-Serrano ◽

Ileana Bladé ◽

Fred Kucharski

Keyword(s):

North Atlantic ◽

Southern Oscillation ◽

Reanalysis Data ◽

Late Winter ◽

Sea Level Pressure ◽

The North ◽

Nao Index ◽

Eddy Heat Flux ◽

The North Atlantic ◽

AbstractThe winter extratropical teleconnection of El Niño–Southern Oscillation (ENSO) in the North Atlantic–European (NAE) sector remains controversial, concerning both the amplitude of its impacts and the underlying dynamics. However, a well-established response is a late-winter (January–March) signal in sea level pressure (SLP) consisting of a dipolar pattern that resembles the North Atlantic Oscillation (NAO). Clarifying the relationship between this “NAO-like” ENSO signal and the actual NAO is the focus of this study. The ENSO–NAE teleconnection and NAO signature are diagnosed by means of linear regression onto the sea surface temperature (SST) Niño-3.4 index and an EOF-based NAO index, respectively, using long-term reanalysis data (NOAA-20CR, ERA-20CR). While the similarity in SLP is evident, the analysis of anomalous upper-tropospheric geopotential height, zonal wind, and transient-eddy momentum flux, as well as precipitation and meridional eddy heat flux, suggests that there is no dynamical link between the phenomena. The observational results are further confirmed by analyzing two 10-member ensembles of atmosphere-only simulations (using an intermediate-complexity and a state-of-the-art model) with prescribed SSTs over the twentieth century. The SST-forced variability in the Northern Hemisphere is dominated by the extratropical ENSO teleconnection, which provides modest but significant SLP skill in the NAE midlatitudes. The regional internally generated variability, estimated from residuals around the ensemble mean, corresponds to the NAO pattern. It is concluded that distinct dynamics are at play in the ENSO–NAE teleconnection and NAO variability, and caution is advised when interpreting the former in terms of the latter.

The Occurrence and Properties of Long-Lived Liquid-Bearing Clouds over the Greenland Ice Sheet and Their Relationship to the North Atlantic Oscillation

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0230.1 ◽

2018 ◽

Vol 57 (4) ◽

pp. 921-935 ◽

Cited By ~ 4

Author(s):

Jonathan Edwards-Opperman ◽

Steven Cavallo ◽

David Turner

Keyword(s):

North Atlantic ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

The Arctic ◽

Positive Phase ◽

Cloud Base ◽

The North ◽

The North Atlantic ◽

AbstractStratiform liquid-bearing clouds (LBCs), defined herein as either pure liquid or mixed-phase clouds, have a large impact on the surface radiation budget across the Arctic. LBCs lasting at least 6 h are observed at Summit, Greenland, year-round with a maximum in occurrence during summer. Mean cloud-base height is below 1 km for 85% of LBC cases identified, 59% have mean liquid water path (LWP) values between 10 and 40 g m−2, and most produce sporadic light ice-phase precipitation. During their occurrence, the atmosphere above the ice sheet is anomalously warm and moist, with southerly winds observed over much of the ice sheet, including at Summit. LBCs that occur when the North Atlantic Oscillation (NAO) is in the negative phase correspond to strong ridging centered over the Greenland Ice Sheet (GIS), allowing for southwesterly flow over the GIS toward Summit. During the positive phase of the NAO, the occurrence of LBCs corresponds to a cyclone located off the southeastern coast of the ice sheet, which leads to easterly-to-southeasterly flow toward Summit. Furthermore, air parcels at Summit frequently originate from below the elevation of Summit, indicating that orographic lift along the ice sheet is a factor in the occurrence of LBCs at Summit. LBCs are more frequently observed during the negative NAO, and both the LWP and precipitation rate are larger in LBCs occurring during this phase. Mean LWP in LBCs occurring during the negative NAO is 15 g m−2 larger than in LBCs occurring during the positive phase.